Process for treating fruit waste



Patented Dec. 29, 1953 UNITED STA? OFFICE 3,664,356 PROCESS FOR TREATING FRUIT WASTE San Jose, Calif.

Jam s R sse l Mefl N9 Drawing. Application July 4, 195

Ser al .N 2 6,849 27 Qiaims- (Cl. 99 2) incidentally therefrom.

More particularly it is an object of the invention to provide a commercial treatment wastes and waste by-products may be easily pumped through flow lines to places of disposition without complication or delay. By the term immediate is meant within a short interval such as around five to thirty seconds,

as later indicated.

A more specific object is to provide a fast and efficient process for thetreatment of deciduous fruit waste, such as apple, peach and pear waste.

Other objects and the various features of the invention will become apparent to those skilled in this art upon reference to the following specification.

Many attempts have heretofore been made to handle fruit wastes satisfactorily, including both deciduous and citrus fruit wastes. with apple, peach and pear wastes, a dition develops which interferes with of the aqueous or liquid constituents of the resultant pulps, and in some treatments the pulp wastes set up as gels in a short time which make juice separation very difficult and render the handling of the wastes by pumps or otherwise commercially prohibitive.

Various agents and procedures heretofore proposed have included, for example, calcium and magnesium carbonate additions in attempts to break the slimes and prevent setting up of gel-like iQrmatiOnS which will not liberate the accompanying aqueous liquids and will not pump. So far as is known, these have all been relatively inefi ective ,or have involved batch standing periods of such length as to be commercially useless For example, up to 5% of calcium" carbonate as been employed the treatment of deciduous fruit wastes but without any efiect in, iminating sliminess. Other agents such as calcium and magnesium hydroxides have been attempted with equally .un-

slimy con- Especially hydroxideis increased to as is necessary to effect quick desliming, the product becomes too heavily d, in ad ing of the ammonlum hydroxide 01' a lapse of five minutes to an hour :or more- Under these conditions only aboutoneh alf per cent'to one per cent or one and one-half per cent (by weight) of 26 Baum ammonium hydroxide discovered that if ammonium (NI-IrOH) is required and only about one per cent to two or three per cent of calcium hydroxide (by weight) is required. The amounts of ammonium hydroxide, calculated on the NHiOH content, are approximately one-half those just given, or about one-fourth per cent to about one-half or three-fourths per cent .NI-IiOI-l by weight, and such is the percentage basis used in the claims. Commonly, the larger proportions of each of these agents is required with riper fruits having higher sugar contents, the less ripe, more commonly processed fruits being satisfactorily treated with the lower proportions. While it is possible ordinarily to employ still larger proportions of the two agents (the calcium hydroxide usually being somewhat in excess of the ammonium hydroxide), such uses generally offer no advantage, render the process unduly costly, and sometimes present real disadvantages. Thus, larger proportions of NHiOI-I may retard the effects on pear waste, may require a long standing time, or may require excessive calcium hydroxide. Strangely enough a mixture of ammonium hydroxide and calcium hydroxide is only slightly more efiective than calcium hydroxide alone, and calcium hydroxide treatment followed by ammonium hydroxide treatment has been found inadequate.

The fruit waste pulp is that characteristically handled in canneries. It commonly contains around ninety per cent of water. It will usually comprise about five per cent solids in addition to its sugar content which may run as high as five per cent and in ripe fruit as high as Thus, in some instances, the water content might be only eighty-five per cent, for example. If desired to facilitate handling, the water content may be increased somewhat, for example to ninety-five per cent. Upon such a pulp, the stated percentages of treating agents are based.

The amount of ammonia (ammonium hydroxide) is introduced in any appropriate water solution, and is commonly such as to yield a pH value of about 8.5 to 9.5 (well above pH 7) in the mentioned deciduous fruit wastes. After thorough admixture of the ammonia with the fruit pulp, the calcium hydroxide is introduced. This may occur within a few seconds following distribution or much later, for example an hour later, as above indicated. cium hydroxide is added in slurry form as hydrated lime. Powdered lime could be worked into the pulp to yield the required hydroxide. This slurry also is thoroughly admixed, and especially when added is somewhat greater in proportion than the ammonium hydroxide as above indicated, even if promptly after thorough ammonia distribution, the sliminess is destroyed immediately, that is, within a few seconds, such as one to five or ten seconds, and the aqueous liquor breaks out so that easy handling, as by pumping, may be effected.

As has been pointed out above, it is necessary that the ammonia treatment, to effect t e stated rise in pH value, be accomplished before the calcium hydroxide is introduced. The reason for this sequence necessity is not entirely clear, although it is known that the ammonia changes the pectous constituents to soluble forms, and that subsequent gel formation is prevented; and it has been found, as previously indicated, that addition of the two agents (ammonium and calcium hydroxides) together produces no advantageous result beyond the use of calcium hydroxide alone, or ammonium hydroxide alone.

Preferably the cal- In the treatments above outlined, sliminess is promptly destroyed upon the calcium hydroxide treatment, and there is no subsequent gelling. Consequently the mass may be easily pumped and filtered.

Examples As examples of acceptable methods of procedure, the following are furnished.

One thousand gallons of pear waste (peelings, cores, trimmings, and discards) are finely pulped and passed into an agitator tank as well understood in cannery practices with a total solids content of 5 per cent to 15% as desired or required for ready handling. To this pulp there is added ammonium hydroxide solution to yield about one-fourth per cent (by weight) of NHiOI-l; for example, nine or ten gallons of 26 Baum ammonium hydroxide (about 30% NH: by weight). This pulp batch is then agitated to effect thorough distribution of the ammonium hydroxide. Normally a pH of about 9.5 results. If calcium hydroxide is to be added promptly after distribution, about one per cent by weight is introduced as a lime slurry, mixed therein and thoroughly blended. As soon as good distribution is eiiected, sliminess immediately disappears, and the juice separates freely from the solids. In fact, at the point of introduction of the lime slurry sliminess disappears within five seconds of introduction. If the same batch has been allowed to stand for half an hour or more with the ammonium hydroxide, half the lime slurry may be used with the same results.

Instead of using calcium hydroxide, barium hydroxide may be substituted, which in some cases is even more effective than calcium hydroxide and may therefore be used in slightly smaller proportions. Thus, perhaps the amount of barium hydroxide may be reduced by about one-fourth over the calcium hydroxide with some fruit wastes, for example, from 1.5% to 1.2%.

When the juice has been separated from the pulp, as by filtering, it may in turn be treated with any appropriate mineral acid such as hydrochloric, sulfuric or phosphoric acids to a pH of less than T or about 4 to 6.5 to precipitate pectous substances which are removed. This applies when barium hydroxide is used, as well as when the hydroxide of any other alkaline earth-metal is used as mentioned. The effluent may then be discarded or treated for recovery of sugar constituents. The pulp from the filter may be used for animal feed, soil treatment, or such other uses as appropriate for any given product.

For a semi-continuous process, the ammoniated pulp is withdrawn from the tank through a flow line and the lime slurry metered into the flow line in proper proportion, the sliminess quickly disappearing so that the juice breaks out at once, the flow being passed to a filter or to a settler.

A continuous operation is effected by metering both the ammonium hydroxide and the calcium hydroxide successively into a flow line through which the pulp is being pumped. The calcium hydroxide is introduced down stream beyond the point of introduction of the ammonium hydroxide sufficiently for complete distribution of the ammonium hydroxide prior to reaching the feed point of the calcium hydroxide (lime slurry). Since the juice break is quick, pumping thus becomes feasible.

Should the fruit be riper, or the pulp be somewhat-zn re re a ed th .ammen m h dro ide i e-meth d is? tr atin ru t an the be increased, for e empi ,te ne perpent, like containing sliming constituents, comprising: and the calcium hydroxide"tonne and one-half producing a pulp from the fruit waste; distributor two per cent. i throughout the pulp a propprtion of ammo,

"Specific percentages which have been used 5 nium hydroxide between about oneefourth per without standing after" incorporating the NHtOH cent and one per cent to produce a pl-lf in the pulp are: l above about ,8; and, thereajter distributing t o gho t the pulp between about oneehalf per 7 Percent Percent Percent Percent Percent Percent (39113 a re 1 3;" m? of an a ka n e rt metal epulpand x hy x de to destroy sliminess m th. NHH 0. 25 0.5 0.25 1 0.5 0.4 $9 8.9 br a in 0 th iq l t constituents from Ca(OH)2.. 1.0 2.0 1.5 3 5.0 2.0

8. A method as Percentages used where standing of one hour claim 7 wherein the alkaline 1d or more was allowed after NHtOH incorporation are: 7

al hydroxide is apy d bl hat. he ammon umhy- I 'oa d i 10. A method as in claim 7 wherein, following the distribution of the ammonium hydroxide in the pulp, such ammoniated pulp is allowed to 25 stand for an appreciable period of time for the 3 11. A method as in claim 7 wherein the alkaline earth-metal hydroxide is calcium hydroxide.

l g tcf ti e izetal hydroxides employed it is to A method as III.) claiim 7 wherein the alkaline be noted that these are divalent alkaline earthig i ifg fi gffif gigg g; db metal hydroxides, to which strontium hydroxide l 0 d 1 h d d maybe added. For this purpose magnesium is 14 A g g g i g y i; 6 d classed as an alkaline earth metal. All of these vaier'lt metal c ii fi g f gig; X1 hyldrogxidez Iare classifitble also as alkaline di- A method as m 01mm 7 Including Swamp en 301111301111 ing the liquid from the sol1d constitu nts, and

I claim as my invention:

1. A method for treating fruit waste and the like containing sliming constituents, comprising: A method forming the fruit waste into a pulp; combining with such pulp a minor proportion of ammonium hydroxide and thoroughly distributing the ammonium hydroxide to yield a pH value of about A method as i t 3' mcotnpmfatlon of sand line earth-metal hydroxlde is sufficient to raise ammonium hydroxide, introducing 111130 such amthe pH to between 10 and 18. A process for treating fruit waste, comprising the steps of: pulping fruit waste; supplysaid ammonium hydroxide and liberate the liquid from the solid constituents.

2. A method as in claim 1 wherein said ammoone-fourth per cent to one per cent of NH4OH used in the proportion of about one-half per cent to four per cent based on the total pulp.

3. A method as in claim 2 wherein the divalent metal compound is an alkaline earth-metal hy- A process fl m 01mm 19 Wherem' IOHOWmg droxide the treatment with said alkaline barium com 4. A method as in claim 3 wherein the alkaline f the pulp is additionally treated with an earth-metal hydroxide proportion is in excess of alkaihne compound P the K conslstmg of the ammonium hydroxide. proportion calcium and magnesium alkaline compounds to A method as in claim 4 wherein the alkaline reduce refractory sliminess further and further earth metal hydroxide is about 1% to 2% of the promote juice Separationpulp and the ammonium hydroxide is about one- A Process according to Claim 0 w fourth per cent t one-.half cent of the pulp. prior to treatment with said barium compound, 6, A method as i l i 1 h i t propgrthe pulp is treated with an ammonium compound tion of ammonium hydroxide approximat oneto initiate IGdUCtiOIl Of refractory sliminess. fourth per cent to one-half per cent of the pulp, 22. A process as in cla m 18 W following and the proportion of alkaline earth-metal comthe treatment with said alkaline barium compound exceeds the proportion of ammonium hypound, the pulp is additionally treated with an droxzde and amounts to about one percent to alkaline compound of the class consisting of calthree per cent of the pulp. 7 cium and magnesium alkaline compounds to reduce refractory sliminess further and further promote juice separation.

23. A process as in claim 22 wherein, prior to treatment with said barium compound, the pulp is treated with an ammonium compound to initiate reduction of refractory sliminess.

24. A process as in claim 18 wherein prior to treatment with said barium compound, the pulp is treated with an ammonium compound to initiate reduction of refractory sliminess.

25. A process for treating fruit waste comprising the steps of: pulping fruit waste; supplying in the pulp a quantity of an alkaline ammonium compound in proportion to reduce sliminess and cause the juice of the pulp to be liberated; and after such treatment with ammonium compound adding thereto a quantity of an alkaline barium compound to further reduce sliminess and effect juice separation.

26. A process as in rating the liberated juice from the pulp treated claim 25 including sepa- 20 with said alkaline compounds, and then acidifying the separated juice to precipitate pectous substances.

27. A process as in claim 25 including the additional step of treating the ammonium and barium treated pulp with an alkaline compound from the class consisting of calicum and magnesium alkaline compounds to reduce refractory sliminess further and further promote juice separation.

JAMES RUSSELL McCAUGHNA.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A METHOD FOR TREATING FRUIT WASTE AND THE LIKE CONTAINING SLIMING CONSTITUENTS, COMPRISING: FORMING THE FRUIT WASTE INTO A PULP; COMBINING WITH SUCH PULP A MINOR PROPORTION OF AMMONIUM HYDROXIDE AND THROUGHLY DISTRIBUTING THE AMMONIUM HYDROXIDE TO YIELD A PH VALUE OF ABOUT 8.5 TO 98,5; AND FOLLOWING INCORPORATION OF SAID AMMONIUM HYDROXIDE, INTRODUCING INTO SUCH AMMONIATED FRUIT PULP A MINOR PROPORTION OF AN ALKALINE DIVALENT-METAL COMPOUND SUFFICIENT TO DESTROYS SLIMINESS IN SAID PULP IN CONJUNCTION WITH SAID AMMONIUM HYDROXIDE AND LIBERATE THE LIQUID FROM THE SOLID CONSTITUENTS. 